This invention relates to electrically operated toothbrushes and more particularly to an oscillating head mechanism for an electrically operated toothbrush.
Electrically operated toothbrushes provide a device for cleaning teeth that has a mechanized bristle head which is operable to effect motion between the bristle head and the handle of the toothbrush to provide a scrubbing action to the teeth to which the bristle head is applied. Electrically operated toothbrushes provide a range of motions between the bristle head and the toothbrush handle to augment the scrubbing action the bristle heads apply to the teeth which are to be cleaned by the toothbrush.
Electric toothbrushes provide an oscillating motion to the bristle head have been described in the prior art including, for example, in U.S. Pat. No. 5,625,916 to McDougall. The disclosure of McDougall describes an electrically driven toothbrush having an oscillating head that is operable by rotation of a rotating shaft coupled to the head which is driven by an electric motor. The mechanism of McDougall provides a limited range of oscillation to the bristle head. Because the bristles extending from the bristle head of a toothbrush are flexible, the motion or movement of the portion of the other end of the bristles in contact with the teeth of a user is reduced from the motion imparted to the bristles by the bristle head. To promote cleaning of the teeth of a user, it is desirable to have an efficacious relative motion or scrubbing contact of the toothbrush bristles to the teeth and gum tissues of the user. Because of bristle flexibility, a limited range of motion of a bristle head can result in bristle end immobilisation when the toothbrush bristles are applied to the teeth or gums of a user. Bristle end immobilisation in has the undesirable result of an inefficacious rocking motion of the toothbrush bristle ends relative to the tooth and oral surfaces that are sought to be cleaned.
It is desirable to provide a range of motion of a toothbrush bristle head of an electric toother brush that facilitates a brushing action to be applied by the toothbrush bristles when engaged with the teeth and oral surfaces to be cleaned.
It is an object of the present invention to provide an electrically operable toothbrush with an oscillating bristle head driven through an efficacious range of motion relative to the toothbrush handle.
In one of its aspects, the invention provides a bristle head oscillation mechanism for an electrically driven toothbrush comprising an elongate housing having a drive shaft rotatably mounted therein. A bristle head is rotatably disposed at an end of the elongate housing and coupled to a pivot arm pivotable about a pivot axis depending from the housing. Opposing ends of the pivot arm are coupled to the drive shaft and to the bristle head respectively. Rotation of the drive shaft pivots the pivot arm to effect oscillation of the bristle head with respect to the elongate housing.
The preferred embodiments of the invention will now be described with reference to the accompanying drawings in which the same reference numerals are used to describe like features of the invention throughout the various figures of the drawings.